Biodiversity loss can lead to total ecosystem collapse

The history of life on Earth has experienced several mass extinctions, the greatest of them being the Permian-Triassic extinction event – also known as “the Great Dying” – which occurred 252 million years ago and wiped out 95 percent of life on our planet. Although most scientists agree on its causes – increased volcanic activity and a subsequent spike in atmospheric carbon dioxide that led to global warming, ocean acidification, and marine deoxygenation – precisely how this event unfolded and led to ecological collapse remains a mystery. 

Now, in a study published in the journal Current Biology, an international team of researchers has analyzed marine ecosystems before, during, and after the mass extinction to clarify the series of events that led to severe ecological destabilization. The investigation revealed that biodiversity loss could be the harbinger of a more devastating ecological collapse, a worrisome finding considering the fact that the rate of species loss today is higher than during the Great Dying.

“The Permian-Triassic extinction serves as a model for studying biodiversity loss on our planet today,” said study co-author Peter Roopnarine, a curator of Invertebrate Zoology and Geology at the California Academy of Sciences. “In this study, we determined that species loss and ecological collapse occurred in two distinct phases, with the latter taking place about 60,000 years after the initial biodiversity crash.”

In order to recreate ancient marine environments, the scientists examined fossils from South China (a shallow sea during the Permian-Triassic transition) and, by sorting species into guilds – groups of species that exploit resources in similar ways – they analyzed predator-prey relationships and determined the functions various ancient species performed. Such simulated food chains helped the experts model the state of the ecosystem before, during, and after the extinction.

“Despite the loss of over half of Earth’s species in the first phase of the extinction, ecosystems remained relatively stable,” reported study lead author Yuangeng Huang, a paleontologist at the China University of Geosciences. However, although inter-species interactions decreased only slightly in the first phase, they dropped significantly in the second one, pushing ecosystems to a tipping point from which they could not recover.

Since ecosystems are more resistant to environmental change when there are multiple species performing similar functions – a phenomenon called “functional redundancy” – biodiversity loss led to an insufficient number of species to perform essential functions and, later on, when global warming and ocean acidification increased, it caused a massive ecological collapse.

These findings highlight the importance of considering functional redundancy when assessing current conservation strategies, as well as the urgent need for action to mitigate biodiversity loss. 

“We are currently losing species at a faster rate than in any of Earth’s past extinction events. It is probable that we are in the first phase of another, more severe mass extinction. We cannot predict the tipping point that will send ecosystems into total collapse, but it is an inevitable outcome if we do not reverse biodiversity loss,” Huang concluded.

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By Andrei Ionescu, Earth.com Staff Writer

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